2020 Department News
Ph.D. students Jerry Wang and Weishi Yuan publish their latest work on Kagome Quantum Spin Liquid in Nature Physics
Each electron in magnetic materials is accompanied by a small entity called the "spin", which acts like a tiny bar magnet. When magnetic materials are cooled down toward absolute zero (-273 degrees Celsius) using liquid helium as a cryogen, these microscopic spins generally begin to align themselves along a certain orientation and form a macroscopic magnet. It is an example of the phenomenon called the phase transition; an every day example of phase transitions is liquid water frozen to form a solid ice when cooled below 0 degree. A holy grail of quantum condensed matter physics today is to identify a magnetic material in "a quantum spin liquid state," which does not undergo such a phase transition even at absolute zero, in analogy with liquid water that never freezes. In 2015, Mingxuan Fu, then a Ph.D. student in Dr. Imai’s group in the Physics and Astronomy Department, used nuclear magnetic resonance (NMR) spectroscopy conducted near absolute zero to detect an early signature of quantum spin liquid state in a mineral material called herbertsmithite. Her dissertation work published in the journal Science, however, left the important issue of spatial inhomogeneity unresolved. A new generation of Ph.D. students in Dr. Imai's group, Jerry Wang from Toronto (standing right) and Weishi Yuan from Beijing (sitting left), came up with a novel approach to tackle this difficult problem; they developed the in-house computer codes for NMR data analysis based on inverse Laplace transform (ILT) techniques, and successfully demonstrated that two electron spins gradually form a pair to prevent a magnetic phase transition from happening in both the aforementioned herbertsmithite and another mineral material called Zn-barlowite. Their ground breaking work, conducted in collaboration with Stanford University and Rice University, has been published in Nature Physics, one of the most prestigious peer reviewed journals in Physics, and can be viewed here.
In May we were devastated to learn of the tragic passing of Sara Etehadolhagh. Sara was a phenomenal student in our medical and biological physics program, but more importantly, she was a fantastic individual: kind, compassionate, and thoughtful. She had a positive impact on everyone she interacted with. Processing her loss is very difficult and I know many in the community are still grieving and will be for some time to come.
In working with her family, friends, colleagues, and classmates, McMaster has put together an iFund Mac page to raise funds for a scholarship in Sara's name here. The Department of Physics & Astronomy has begun the fundraising effort with a donation of $5000. If you are able, we encourage you to donate in Sara's memory. The scholarship will support women in the medical and biological physics program.